Current wireless communications devices include a radio incorporated on an integrated circuit chip. Antennas are used to transmit and receive the wireless signals. Antennas are implemented as conductive lengths of material having a variety of shapes to optimize reception and transmission properties. As a general rule, antenna lengths range from a half wavelength to under one tenth wavelength of the transmitted or received signal, depending upon the antenna configuration and the level of acceptable performance. The wavelength λ is determined for a given frequency f by the formula c=fλ, where c is the speed of light, approximately 3×108 m/s. For a 2.4 GHz signal, as used in Bluetooth and IEEE 802.11 wireless standards, λ=12.5 cm. Thus, for a 2.4 GHz signal transmitted from or received by a dipole antenna, maximum transmission and reception capabilities are achieved when the antenna length is an odd multiple of the received signal's quarter wavelength (λ/4), or 3.125 cm. Because of capacitive end effects of the antenna, the actual antenna length usually has optimal performance at about 95% of the length of a quarter wave length of the received or transmitted signal. Space must be found to accommodate the antenna and allow for adequate transmission and reception.
Current wireless devices have certain deficiencies. One deficiency in current devices is inefficient use of available space in the incorporation of an antenna. For example, there are unused areas in the wireless device chip packages, the circuit boards to which they mount, and the space between the chip packages and the circuit board which is underutilized. Furthermore, to generate a separate antenna element which is added to the wireless device increases the volume of the device. Thus, wireless communications devices are not as compactly made as they could be. Additionally, this adds to the total weight of the wireless device which may burden a user who carries one for an extended period of time.
Another deficiency is the manufacturing cost of portable wireless devices. Incorporating an antenna in current devices which also package a radio and baseband adds an additional step in the manufacturing process which increases costs. Although per unit costs of wireless devices may not be very high, minor cost savings on a per unit basis add up in the context of economies of scale. This is true for the manufacturer which produces large numbers of units as well as organizations which use many such devices.
Therefore, it would be desirable to have antennas which reduce the size and manufacturing cost of wireless communications devices in a wireless local area network.